The invention aims to provide a method for producing X70 pipeline steel by using a TMCP type plate
assembly with the length of 3 times of length. The method comprises the following steps: adopting low C and low S as components, ensuring that the outbound
hydrogen content of refined
molten steel is less than 1.5 ppm, performing hot charging and hot delivery on a 260mm
continuous casting blank, performing plate
assembly on a mother plate with the length of 3 times of length, cooling after rolling, changing the water quantity and the roller speed to control cooling compensation, and performing temperature
pile cold
hydrogen evolution after edge
cutting, so as to obtain the X70 pipeline steel with the TMCP type length of 3 times of length. The thickness specification of 12-25 mm is achieved, and the width meets the
pipe diameter phi of 1016 mm. The process
route comprises the steps of converter BOF, refining,
continuous casting, plate blank hot charging and hot delivery (cooling to below 550 DEG C through a
water cooling device before charging), TMCP, finishing (rapid stack cooling and fixed-length marking after trimming) and finished product obtaining, the structure mainly comprises
bainite and
acicular ferrite, the strength difference of the head, the middle and the
tail is within 50 MPa, the steel plate performance meets the steel grade requirement, and the production cost is low. The flaw detection of the steel plate can meet the level that 10dB is added on the basis of the ISO10893-9-2011-A1-2020 (detection of layered defects in a strip plate for manufacturing the ninth part of welded steel pipes in
nondestructive testing of steel pipes) standard.